How to make correct path of files if global variables change?

[toplisek]

I have seen that on new server is changed:
New server
[REQUEST_URI] => /
[SCRIPT_NAME] => /index.php

Old server showed me:

[REQUEST_URI] => /index.php
[SCRIPT_NAME] => /index.php

What will influence this variable? Need help.
I had in old server:$_PATH1 ="http://" . $_SERVER['HTTP_HOST']."/";

Now it does not work anymore path.